Oak (Stejar)

Oak (Stejar)

Wood Density

The weight per m³ of oak wood is quite high, around 675 kg.

Janka Hardness Test

The Janka hardness test is useful to directly determine how well a wood resists impacts, wear, and accidents, and also indirectly predicts nailing, screwing, and sanding difficulty. The Janka hardness result for oak is 4980 N.

Bending Strength

Bending strength measures a species' resistance before breaking. It can be used to determine the overall strength of a wood species. Unlike the modulus of elasticity, which measures wood deformation but not final strength (some woods may bend under stress but not break easily). The bending strength for oak is 97.1 MPa.

Modulus of Elasticity

The modulus of elasticity measures the stiffness of wood and is a good general indicator of its strength. According to tests, oak has a modulus of elasticity of 10.6 GPa.

Compressive Strength

Compressive strength parallel to the grain measures the maximum crushing resistance when force is applied to the ends of the wood. According to tests, oak has a compressive strength of 46.3 MPa.

Wood Swelling and Shrinking

These are very important phenomena that occur in wood as the moisture content in the cell walls changes, causing variations in its dimensions and volume as water enters or leaves the wood. Considering the hygroscopicity of wood, these phenomena are permanent and pendular in nature, also called wood movement. They cannot be prevented but can be reduced through various wood stabilization methods. Swelling increases wood dimensions and volume, while shrinking decreases dimensions and volume due to reduced bound water content.

Radial swelling and shrinking = 4.7%

Tangential swelling and shrinking = 8.4%

Volumetric swelling and shrinking = 13%

Color/Appearance

The heartwood ranges from light to medium brown, usually with an olive tone, though there can be significant color variation. Sapwood is nearly white to light brown and is not always well-defined from the heartwood.

Grain/Texture

Grain is straight with a coarse, uneven texture, featuring large rays and pronounced parenchyma zones. The fiber may be irregular or twisted depending on the tree's growing conditions.

Durability/Rot Resistance

European oak is considered very durable against decay and is commonly used in boat building applications.

Odor

Has a characteristic odor common to most Quercus species, with a tannin scent.

Allergies/Toxicity During Processing

Although severe reactions are rare, oak may irritate the eyes, skin, or cause asthma-like symptoms.

Price/Availability

Widely cultivated and available throughout Europe, oak is not very cheap due to its extremely low yield.

Sustainability

This species is not listed in the CITES appendices and is reported by IUCN as a species without growth concerns.

*Information sourced from wooddatabase